Shaking Table Model Test And Numerical Simulation Study Of Soil-Subway Station-Surface Seismic Isolation Structural System

As a lifeline project,the underground railroad system is assuming an increasingly important role in China’s urban transportation system.At present,the seismic safety of underground structures,especially large subway station structures,the influence of underground structures on the urban seismic environment and the dynamic interaction between soil-underground structures-surface structures have become important issues to be studied urgently.Based on this,the shaking table model test of soil-subway station-surface seismic isolation structure system and its numerical simulation are carried out in this paper by combining experimental research and numerical simulation.The main research works and results of this paper are as follows.(1)Shaking table model test design of soil-subway station-surface isolation structure system.Based on the shaking table size,operating frequency and vibration mode of the State Key Laboratory of Civil Engineering Disaster Prevention,Tongji University,the test similarity ratio was determined,and the model structure and model soil for the shaking table model test of soil-subway station-surface isolation structure system were designed.The input waves of the 1985 Mexico earthquake,the 1999 Taiwan-Chichi earthquake and the 2003 Tokachi earthquake in Japan were selected as the input waves,and the shaking table model test conditions were set up for the free field of the site,the soil-subway station structure interaction system,the soil-subway station-surface uncontrolled structure system and the soil-subway station-surface isolation structure system.On this basis,the transfer function verification of the seismic response of the site and the boundary effect test verification of the model soil box were carried out using the frequency domain method of Kramer(1996).(2)Shaking table model test study of soil-subway station-surface seismic isolation structure system.Based on the shaking table model test conditions,a series of shaking table model tests were conducted for the site free field,soil-subway station structure system,soil-single surface structure system,soil-subway station-single surface structure system,soil-surface seismic isolation structure and surface uncontrolled structure comparison system,and soil-subway station-surface seismic isolation structure and surface uncontrolled structure comparison system,respectively.The results show that the presence of the subway station decreases the seismic response amplitude at the surface of the site directly above it,and increases the seismic response value at the site next to it;the surface structure decreases the surface response value of the model soil,and the degree of influence is related to the spectral characteristics of the input seismic waves.The underground subway station structure has a certain influence on the acceleration response,displacement response and interlayer displacement values of the surface structure,and the reduction of the amplitude in the high frequency band is obvious;compared with the surface uncontrolled structure,the surface isolation structure can weaken the "subway station effect" to a certain extent.(3)Numerical simulation of the shaking table test of the soil-subway station-surface isolation structure system.The finite element model corresponding to the shaking table model test series in Chapter 2 was established using ABAQUS software,and numerical simulations were carried out according to the shaking table model test conditions.The reliability of the finite element numerical model was verified by comparing the results with the acceleration and displacement responses of the measured points in the test model under the corresponding working conditions.On this basis,the numerical simulation and parametric analysis are focused on the shaking table test of the soil-metro station-surface isolation structure system;the response characteristics of this interaction system under the action of Ricker waves are analyzed by introducing dimensionless frequency parameters η.The results show that the interaction effect of soil-Metro station-surface structure decreases the acceleration amplification coefficient and displacement response peak value,but increases the inter-story displacement,column axial force,column shear force and stress amplitude of the metro station structure;the degree of influence of the surface structure on different components of the metro station structure is related to their relative positions,and the closer the metro station is to the components of the surface structure,the more obvious the influence is.The closer the subway station is to the surface structure,the more obvious the influence is.For Ricker wave effects with different dimensionless frequency parameters η,the seismic isolation structure is outstanding in reducing the inter-story displacement of the structure,which proves the insensitivity of the sliding plate isolation bearing to the input frequency.(4)Analysis of the ground vibration coherence function and seismic response of subway station structure with the change of site depth.At present,the research on the coherence of ground shaking at home and abroad is basically limited to the coherence model along the ground surface.In this paper,2,679 pairs of ground shaking records were selected from the Japanese KiK-net strong-motion observation network,and the ground shaking was classified according to soil cover depth and shear wave velocity,and the characteristics of ground shaking along the depth of the site were analyzed under four different site conditions by using digital signal processing methods.regression analysis.On this basis,the bedrock ground vibrations that meet the correlation requirements along the site depth are obtained by using the Kriging difference estimation method,and a 3D finite element analysis of a typical subway station structure is carried out with the bedrock ground vibrations as input.The results show that the coherence function of the horizontal component of ground shaking decays exponentially with increasing frequency;the coherence function of the vertical component of ground shaking decays exponentially at the beginning,and then increases to a certain value at a certain frequency and continues to decay,and the frequency value is related to the site conditions.The coherence function of ground shaking with the depth of the site decays exponentially with the increase of distance and frequency;the coherence of the high-frequency component of ground shaking decays significantly faster than the low-frequency component with the increase of distance;the coherence of the same component of ground shaking is significantly different in different types of sites,and the softer the site,the weaker the coherence.In the example of seismic response of subway station structure in this paper,the maximum amplitude of inter-story displacement is at the mid-span of the ground floor of the subway station structure.(5)Seismic response analysis of soil-metro station-high-rise structure interaction system under strong seismic effects.A subway station and its adjacent high-rise buildings are used as the background to establish the three-dimensional finite element models of soil-subway station interaction system,soil-high-rise structure interaction system and soil-subway station-high-rise structure interaction system,and the ground vibration input time range of bedrock is obtained by using the ground vibration coherence function method based on the change of depth with site in Chapter 5 of this paper.The effect of the high-rise structure on the seismic response of the subway station is analyzed.The results show that the presence of the subway station increases the seismic response of the adjacent high-rise structures,and the degree of increase varies unevenly with the floor height,with the most significant effect in the middle and upper parts of the high-rise structures,and the maximum inter-story displacement increases up to 30%.The spacing L between the high-rise structure and the subway station,the burial depth D of the subway station structure and the input ground shaking spectrum components are the main factors of interaction.In this paper,the effect of the subway station on the high-rise structure is negligible when D=3m,L≥10m or when L=5m,D≥20m,the effect of the subway station on the high-rise structure is negligible;when the input ground shaking spectrum components are widely distributed,the effect is obvious.In general,the presence of surface high-rise structures reduces the seismic response value of the subway station structure;the effect of surface high-rise structures on the response of the top layer of the subway station structure is more obvious compared with the bottom layer of the subway station structure.